Overview

Error 90003945 is a product listing validation error that Amazon returns when a value submitted for a specific attribute is not compatible with other attribute values already selected in the listing. This conditional validation means that certain field values are only valid when paired with specific precondition values, and submitting an incompatible combination will block the listing from being created or updated. Understanding how preconditions work is essential for sellers who manage catalog listings through flat files or feed submissions.

Key Points / What Sellers Need to Know

• Precondition-based validation — Amazon validates certain attribute values against a set of precondition fields. If the combination of values across those fields is not allowed, the submission will be rejected with this error.
• Error format — The error message specifies exactly which precondition fields, which attribute, and which invalid value triggered the rejection, making diagnosis straightforward once you understand the structure.
• Template reference is essential — The valid values sheet included in Amazon's product listing templates contains the approved combinations of precondition values and their corresponding allowed attribute values.
• Common in apparel and size-related listings — This error frequently appears when listing products with size attributes, where valid sizes depend on factors like size class, size system, age range, and target gender.
• Feed and flat file submissions — Sellers using bulk upload methods through flat files or feed submissions are most likely to encounter this error, especially when reusing templates across different product types.

How This Error Works

Amazon's catalog system enforces conditional validation rules on many product attributes. Rather than allowing any value in a given field, the system checks a set of precondition fields first and then determines which values are permissible for the target attribute. For example, when listing shapewear products, the valid values for the "size" attribute depend on a combination of the shapewear size class, size system, age range description, and target gender. If a seller submits a numeric size value like "80" but the selected preconditions do not support that size, Amazon will reject the submission with Error 90003945. The error message itself identifies both the precondition fields and the invalid value, which gives sellers a clear starting point for troubleshooting.